Pope John Paul II, who served as the spiritual leader for the world’s 1 billion Roman Catholics for 26 years, died Saturday night at the age of 84.

"The Holy Father died this evening at 9:37 p.m. (2:37 p.m. EST) in his private apartment,” said Vatican spokesman Joaquin Navarro-Valls, as reported by the Associated Press. “All the procedures outlined in the apostolic Constitution `Universi Dominici Gregis' that was written by John Paul II on Feb. 22, 1996, have been put in motion.”

Yesterday afternoon, Navarro-Valls told journalists in a statement that the general conditions and cardio-respiratory conditions of the Pope had further worsened.

"A gradual worsening of arterial hypotension has been noted, and breathing has become shallow,” the spokesman said.

At 11:30 this morning (4:30 a.m. EST), Navarro-Valls held a briefing for accredited journalists in the Vatican press office to give an update on the condition of the Pope.

"The general, cardio-respiratory and metabolic conditions of the Holy Father are substantially unchanged and therefore are very serious,” Navarro-Valls said, according to a statement released by the Vatican.

"As of dawn this morning, the start of a compromised state of consciousness was observed.”

According to AP, John Paul's health declined sharply Thursday when he developed a high fever brought on by a urinary tract infection that also led to blood poisoning. The Vatican said the Pope also suffered septic shock and heart problems during treatment for the infection.

In the past two months, the Pope had spent a total of 28 days in two stints at Rome's Gemelli hospital. He suffered from a number of chronic illnesses, including crippling hip and knee ailments and Parkinson's disease--a progressive neurological disorder that can make breathing difficult.

After news of the Pope’s passing made its way to the public late Saturday, Cardinal Angelo Sodano, Vatican City's Secretary of State, led a tearful crowd of 70,000 people in St. Peter's Square in prayers for the beloved pontiff.

According to AP, some people held their hands to their heads in disbelief. Others cried uncontrollably as they stood in the massive plaza beneath the Pope's still-lighted apartment windows.

AP reports that a Mass has been scheduled for St. Peter's Square for 10:30 a.m. (3:30 a.m. EST) Sunday.

Now, regarding who will succeed one of the longest-serving and most contentious figures in papal history, sources say that the College of Cardinals would be meeting at the Vatican in the coming days to select the next pope.

Already cardinals from around the world had reportedly begun heading to Rome, most likely in preparation for the pontiff’s death.

“After he passes away, the College of Cardinals will meet,” explained Mark Brumley, author on Pope John Paul II and president of the largest Catholic book publishing company in America. “The cardinals are literally locked up in the Sistine chapel until they can vote on a successor.

“A two-thirds vote is needed in the choice,” Brumley continued. “But if they go 12 days into this, the cardinals may change the rule and elect with a simple majority.

“We don’t know if it will take that long, but in this century the process typically took two to four days.”

Sources say the cardinals will hold the clandestine meeting within 15 and 20 days after the passing of a pope in order to choose a successor from among their numbers.